Currently available apparatuses that measure power parameters in a RF power transmission system typically utilize inductive type pickup coils positioned transverse to a connected transmission line. The coils sense voltage variations related to forward- or reverse-traveling voltage waves on the transmission line and this voltage is rectified and used to drive an analog meter displaying a human perceptible value. However, these types of devices are not capable of measuring complex impedance which is an important quantity in RF power calculations.
In addition, current instruments generally use electrical assemblies containing an inductive pickup coil, a resistor-capacitor frequency compensator, and a diode rectifier to provide a direct current (“DC”) signal related to forward- and reverse-traveling waves on the transmission line. A deficiency with this type of design is that the assembly will only accommodate a relatively limited frequency range of, for example, 25-60 MHz or a ratio of approximately 2.5:1, with a “feasible” ratio of 5:1. Additionally, such configurations accurately measure a relatively small range of RF power (e.g. 150 to 1000 Watts or a ratio of about 7:1).
These aforementioned limitations result in several different assemblies being required to accommodate even a modest range of frequencies and RF power amplitudes, and such assemblies are relatively expensive due to precise machining and high quality componentry required to achieve a high quality, high directivity directional coupler. Hence, what is needed in the industry is a relatively inexpensive RF meter that is able to accurately measure all of the RF power parameters required to optimize a radio frequency transmissions source.